The present invention relates to a cleaning gas for removing an unnecessary deposit deposited on an inner wall and tools of a thin film producing apparatus by means of CVD method, and relates to a method for cleaning a vacuum treatment apparatus by the cleaning gas.
In various production processes for producing thin-film devices, optical devices and super steel materials, various films, powders and whiskers are produced by means of CVD method, sputtering method, sol-gel method and vapor deposition method. By the execution of the above-mentioned methods, unnecessary depositions are deposited on an inner wall and tools of the producing apparatus. In order to prevent such unnecessary deposit from affecting objective products, it is necessary to properly remove such unnecessary deposit. A cleaning gas employed to remove such unnecessary deposit is required to have several performances. For example, such a cleaning gas has to perform so as not to damage the objective products, not to increase the amount of particles in a reactor of the apparatus, to be easily varied into innocent gas and to tenderly affect the earth.
Presently, a plasma cleaning employing a cleaning gas of at least one of C2F6, CF4, C4F8, NF3 and ClF3 and a plasma-less cleaning employing a cleaning gas of at least one of F2, Cl2 and ClF3 have practically been executed to remove unnecessary deposits. However, these methods have several problems such that when the cleaning is executed by using the above-mentioned fluorine series gas, heat-resisting Ni-alloy, stainless steel and AlN are corroded by the gas and particles are increased in the apparatus, and that if the temperature for cleaning is lowered to suppress such corrosion, an idling time thereof is increased to lower the throughput of the apparatus, and that if the temperature for the cleaning is lowered to prevent the corrosion of the material of the apparatus, the cleaning speed is lowered.
A Japanese Patent Provisional Publication No. 8-295600 discloses a method for cleaning a nickel base plate employed to produce whiskers of TiC, TiCO and TiCN by means of diluted nitric acid. However, this method requires executing a wet cleaning in an in-site cleaning, and therefore it becomes difficult to improve the throughput of the apparatus.
It is therefore an object of the present invention to provide an improved cleaning gas which effectively removes unnecessary deposit deposited in a vacuum treatment apparatus while satisfying performances required to such a cleaning gas.
A aspect of the present invention resides in a cleaning gas for removing a deposited material generated in a vacuum treatment apparatus for forming a thin film of at least one of Ti, W, Ta, Ru, Ir, a compound including one of Ti, W, Ta, Ru and Ir and an alloy including one of Ti, W, Ta, Ru and Ir, the cleaning gas comprises HF gas and oxygen containing gas.
Another aspect of the present invention resides in a method which functions to remove a deposited material generated in a vacuum treatment apparatus for forming a thin film of at least one of Ti, W, Ta, Ru and Ir, a compound including one of Ti, W., Ta, Ru and Ir and an alloy including one of Ti, W, Ta, Ru and Ir. The method comprises a step of flowing a cleaning gas in the vacuum treatment apparatus.